Love my 2010 is250 which is now due for 30k service. Obtained quote from Lexus dealer $680 compared to my local mechanic $380 (he will also supply genuine parts). So I'm thinking of using the local mechanic who also services Mercs and BMW, we have used them for past 10yrs and never have had any problems.I know Lexus provide loan vehicle and wash/vac the car but is there any other reason for having the car serviced by the Lexus service center.

A 30K service is only oil, filter & brake fluid change. Over here in NZ that be about $300-$350 max at Lexus service agent. Whats the labour rate over there??
As long as your local mechaninc is using genuine parts & oil that meets factory specs or better (i.e. synthetic 5w-30) then there should be no reason it would effect your warranty.
Having your car serviced at the agents does have it's advantages though. Campaign, tsb & warranty issues will be sorted. PCM updates done. Someone working on your car that is factory trained & very familair with the vehicle etc etc.

As long as you get the service done by a licenced mechanic, factory warranty remains valid. Don't let a dealer convince you otherwise.

Yes I didn't see any point in using dealer service, 30k service doesn't seem too complicated or specialised that it requires high tech or specialised equipment. The pcm updates are not are a big issue. Will post again if any problems. Thanks for the advice..

If you're using decent oil then you're just wasting your money dropping it every 5K. The average synthetic like Castrol Edge 5w-30 will be good for at least 10K-15K. If you're that concerned get a UOA (used oil analysis) done to see how well it's holding up.

If you're using decent oil then you're just wasting your money dropping it every 5K. The average synthetic like Castrol Edge 5w-30 will be good for at least 10K-15K. If you're that concerned get a UOA (used oil analysis) done to see how well it's holding up.

Its not wasting money. for is350, you will feel the different if oil change at 10k. once you change it, the revs feel alot better and smoother. ( I can really feel it, I never regret change every 5k ). its only oil and it cost $70 every 5k , better than stealership charge $680. plus your drive feels better, engine last longer.

What oil are you running?? It can't be designed for long drain intervals. I've run a few different synthetic 0/5w-30 (Mobil, Castrol, Takumi etc) in my 3SGE & even when I went out to 12K once I didn't notice any difference with the new oil. It was still pretty clean when it came out too.
Admittedly some engines are harder on oil than others & the 2GRFE has the odd problem with VVTi pulleys which may be due to this. Spend another $20 & get some Mobil1 or Shell Helix Ultra you can leave in for 10-15K. Oil & tyres are two things I wont skimp on.